The present ivnention relates to a method for joining a structural member made of a synthetic resin such as fiber reinforced plastic (FRP) with a further synthetic resin or other structural member. The method is effective when using synthetic resin members instead of conventional lumber or steel members in a main framework of a cooling tower. FRP members increase the corrosion resistance and simplify the assembly of such towers.
There have been used many structural members made of synthetic resins instead of lumber and metals. However, such synthetic resin members have been hardly used as structural members which will receive a heavy load.
For instance, in the field of a cooling tower for cooling warm water through direct contact with a large quantity of surrounding air, synthetic resin members have been used only partially for a small-sized cooling tower for air-conditioning or the like.
Generally, a larger-sized cooling tower used in various chemical industries has a main framework made of lumber or steel. Though being typically composed of Douglas fir lumber processed for pressure-preservative treatment or steel members plated with zinc hot dip galvanizing, a main framework still tends to be easily corroded since the framework of a larger-sized tower cooling atmosphere of is in an extremely high temperature and extremely high humidity.
The frameworks composed of lumber or steel members will begin to be corroded in about ten or 7-8 years' time, respectively, at and around the upper portion of the framework adjacent to a distribution system, which requires repairing of the tower.
As the corrosion spreads, corroded lumber pieces or rust particles will disperse into the cooled water, which may result in deterioration of performance of the cooling tower such as clogging of strainer means in the water-cooling system or increase in pump loads.
Therefore, it may be proposed to construct the main framework using synthetic resins such as FRP which have a high degree of corrosion resistance even in the corrosive atmosphere. However, there are many points to be considered, prior to use of FRP, such as the buckling strength of FRP, influence on the strength of FRP due to absorption of water and its anti-weathering capability. Furthermore, structures for joining of synthetic resin structural members such as FRP members must be developed.
The present invention was made to overcome the above and other problems encountered in conventional cooling towers and has for its object to enable a synthetic resin structural member to be readily and securely joined with a further synthetic resin or other structural member.
The inventors made extensive studies and experiments of anti-corrosion of structural materials to find that synthetic resins are employable for structural members; e.g., FRP members may be used to compose a main framework of a cooling tower.
In order to attain the tasks of the present invention, when a hollow synthetic resin structural member is to be joined by a bolt with a further structural member or members, the bolt is inserted into the hollow member through said further structural member(s) and a distance piece is fitted in the hollow member and then is tightened so that a secure joint between the structural members can be ensured without causing deformation in cross section of the hollow structural member.
When synthetic resin structural members are to be joined together, a connector with a plurality of previously drilled holes is joined to the structural members by drilling holes in the structural members in alignment with the holes of the connector and striking blind rivets into the thus drilled holes one by one. Therefore, the blind rivet holes have a substantially uniform degree of accuracy and the joint work at a site or field is facilitated.
When a hollow synthetic resin structural member is to be joined with another synthetic resin structural member, a connector is attached to the hollow member by means of bolting through a distance piece fitted in the hollow member so as to prevent deformation in cross section thereof. The connector is then joined to the other structural member by blind rivets. While reducing the number of blind rivets to be struck and thus relieving the riveting work or operation, a secure joint between the structural members can be ensured.
The present invention will become more apparent from the following description of preferred embodiments thereof taken in conjunction with the accompanying drawings.
The same reference numerals are used to designate similar parts throughout the figures.